Solid blocks of expended foam plastic have been used for many years to support docks, boathouses and the like on the water. Sometimes these units have been painted or sprayed with a coating. These flotation units have been attached to wooden decks and boathouses by various methods such as plastic straps, metal straps and various fasteners. It is a real problem attaching the flotation devices to other structures such as docks and boathouses and very often the attachment does not last very long. Sometimes it is necessary to drill a hole completely through a plastic block so as to install a threaded rod. Furthermore, such plastic units tend to be destroyed from use and are easily broken if struck by a boat or by rough weather. Encapsulation of plastic foam is a process previously known in other fields such as the transformer mounting pad disclosed in U.S. Pat. No. 4,023,755. The apparatus and procedure for thermoforming is previously known and disclosed in U.S. Pat. Nos. 3,914,103; 3,914,104 and 3,910,747 as well as application for U.S. letters patent Ser. No. 07/106,101. Various plastic units exist in the prior art which could be used as flotation device such as those disclosed in U.S. Pat. Nos. 3,511,191 and 3,581,681. Some of the plastic units are made by creating an open, hollow shell and pouring or injecting the foam materials inside. This is not the same as thermoforming by a vacuum and shrink forming procedures. The primary disadvantage of the previous units has been the difficulty in attaching the units to something else such as a boat dock or a deck. The present device provides a method of attaching the floats by means of strips of plastic such as polyethylene encapsulated inside the float. Then the float unit can be attached directly to a dock by bolting it in place with standard lag bolts.